docs: def _filter_by_moys_slow(self, moys):
          """Filter the Data Collection with a slow method that always works."""
          _filt_values = []
          _filt_datetimes = []
          for i, d in enumerate(self.datetimes):
              if d.moy in moys:
                  _filt_datetimes.append(d)
                  _filt_values.append(self._values[i])
          return _filt_values, _filt_datetimes